lua-factory: fix use of wrong grl_data_set_int
lua-factory: fix use of wrong grl_data_set_int

commit 1e20497737db94c0932a12b4395859 changed the behavior and current
tests got it. grl_data_set_int64 should be used with G_TYPE_INT64 or
else we would fail with:

data/grl-related-keys.c:253: value has type gint, but expected gint64

https://bugzilla.gnome.org/show_bug.cgi?id=755447

GNOME/grilo-plugins,MikePetullo/grilo-plugins,jasuarez/grilo-plugins,grilofw/grilo-plugins,MikePetullo/grilo-plugins,GNOME/grilo-plugins,grilofw/grilo-plugins,jasuarez/grilo-plugins,MikePetullo/grilo-plugins